1. Field of the Invention
The present invention discloses a method of heating a thermal print unit of a dye sublimation printer, and more particularly, to a method of heating a thermal print unit by uniformly distributing a heating duration of the thermal print unit for preventing the thermal print unit from cooling for an overlong duration.
2. Description of the Prior Art
One conventional dye sublimation printer includes a thermal print module, which includes at least one thermal print unit arranged in a row. While the conventional dye sublimation printer is used for printing data on a sheet, the data is printed row-by-row on the sheet by moving the thermal print module row-by-row, where dots on a single row of the sheet are simultaneously and respectively touched and printed by the at least one thermal print unit of the thermal print module. For brevity of description, the following description will be based on a single thermal print unit of the thermal print module, instead of all of the thermal print units of said thermal print module.
While one conventional dye sublimation printer prints data on a sheet, a thermal print unit is gradually heated from a cooling state, which corresponds to a lowest color level, until a certain dot of the sheet touched by the thermal print unit is changed by its color level to reach a target color level. Then, the thermal print unit is ceased heating and then gradually cooled down, until the thermal print module is moved to a next row on the sheet, then the thermal print unit is gradually heated again to another target color level and is gradually cooled down again. Note that thermal print units on the thermal print module may acquire different and independent target levels while the thermal print module prints a single row.
However, the heating on the thermal print unit mentioned above may cause insufficiency of heating on the certain dot of the sheet while the thermal print unit is gradually cooled down, in comparison to the heating while the thermal print unit is gradually heated; and as a result, the heating on the certain dot by the thermal print unit is not uniform as well. While observing the unbalanced heating on the heated sheet by the thermal print module with the aid of naked eyes, the phenomenon could be easily observed so that the printing performance of the dye sublimation printer is apparently degraded.